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The amphibians They are vertebrate animals, in fact they were the first vertebrates that passed from the waters to the mainland. Eg. toad, frog, salamander.
In the past, amphibians represented a very important group of animals, both for the number of species that existed and for the large body size they had. However, they were later evolutionarily overtaken by reptiles, this group being reduced to a few categories.
Amphibians are estimated to have arisen from fish about 360 million years ago, and that reptiles later developed from them, which in turn gave rise to today's mammals and birds.
Examples of amphibians
- Common toad
- Giant toad
- Salamander
- Triton
- Poisonous frog
- New Zealand frog
- Seychelles frog
- Tree frog
- Blue arrow frog
- Axolotl or or ajolote (Mexican salamander)
- Cecilia
- Pygmy flatfoot salamander
- Jalapa false newt
Amphibian characteristics
Amphibians have the bare skin, breathe through gills and they have no legs when they are young; when they are adults they breathe through lungs and have four legs with interdigital membrane.
In addition, they undergo metamorphosis, that is, they go through different phases of life, mainly three:
- That of egg
- The larval (of gill breathing)
- The adult (of lung respiration).
In fact, they are the only vertebrates to undergo metamorphosis.
Some features:
- Adult amphibians can live in water or on land (semi-terrestrial life), larvae can only live in water.
- Amphibians breathe through the skin (cutaneous respiration), to keep the skin moist and prevent desiccation, they have glands through which they secrete mucus.
- They are animals of external or internal fertilization and oviparous.
- They do not have hairs or scales.
- They feed on insects, worms, slugs, and spiders; also vegetables or small mammals, as well as fish and larvae.
- When the external temperature is very low, they tend to remain inactive, and often survive thanks to the reserve of fats that they have accumulated in their body.
- These are animals that gobble up their food without breaking it down previously.
- They have a characteristic organ, the cloaca, which acts as the only exit orifice with urinary and reproductive function.
Classification
There are three orders or classes of amphibians:
- Gymnophiona or apodal (without limbs)
- Caudata or caudates (with tail)
- Anura or anurans (frogs and toads).
It is estimated that there are some 4,300 species of amphibians that live today, but by the way it is a biological group whose populations have been in clear decline for some time in this part, mainly due to the alteration of their natural habitat and climate change.
